Surgery to implant prostheses often requires the surgeon to hold and orient an implant during the implantation. Such holding and orientation often is assisted by use of instruments that hold the implant and provide reference surfaces used to position the holder, and therefore the implant which it holds, relative to some body landmarks. Many size implants are employed by the surgeon, hence it would be desirable for the holder to accept all size implants to minimize the number of different instruments needed to hold these different sized implants.
Particularly difficult problems are associated with implanting metal acetabular hip cup shells which are to be fixed to the bone and into which a plastic bearing is inserted. Such cups are typically available in a large number of inside and outside sizes. Current practice is to hold the cup on its inside surface with an instrument that matches the particular size of the surface. Thus most holding instruments are designed with removable holding heads of various sizes. The instrument system needed to hold a large variety of sizes needs to have a large variety of holding heads and is therefore complex.
A further disadvantage of current cup holding methods is that access to the inside surface of the cup is blocked. Although such access is not always needed, there are occasions where such access is desirable. For example, after the acetabular cavity has been prepared and the cup has been positioned, the cup may be impacted in the cavity, and screws may be added to augment the press fit fixation. In many cases, however, defects in the acetabulum make stable, press fit fixation impractical. In such cases it is desirable to hold the cup with the holder while the screws are added. Current cup holders do not allow this option.
The object of this invention is to provide a holding system where one holder can accept all size components in a way which minimizes restriction of access to the surfaces of the implant.
Another object is to provide a holding system where cup impacting tools, screws and screw drivers may be used in the cup while the cup is being held.
A further object of the invention is to provide a holding system which avoids interference with the bone.